You have to hand this much to Ralph Nader: He can take the heat. Despite pleas and bluster from labor leaders, environmentalists, and feminists to drop out and effectively throw his support to Vice-President Al Gore, the 66-year-old left-wing crusader stayed his lonely course. Even as it became clear that Nader's Green Party candidacy could tip the election to George W. Bush, a politician he rates a ''D minus,'' Nader didn't shy from the role of principled spoiler. And when it appeared that Gore, whom Nader dismisses as just a ''D plus,'' might go down in defeat, Nader called him 'the least of the worst' and said it would serve the Veep right.

That's not the way politics is done in Washington, of course. A more pragmatic Nader would have traded his troops for the right to pick the next Interior Secretary in a grateful Gore Administration. Instead, Nader reveled in his giant-killer status. His allies on the left are apoplectic that he would so cavalierly sink their candidate and risk handing the Republicans the right to radically alter the makeup of the Supreme Court, for example. Says one AFL-CIO official: ''His people are not coalition-builders. We'll never work with him again.''

NO ILLUSIONS. But Nader, who got just under 3% of the vote nationwide, is betting otherwise. If unions and moderate environmental groups ''can put away the recriminations, they will find that we are allies of their interests and they are allied with ours,'' Nader insists. Says pollster John Zogby: ''A Ralph Nader comes along very rarely. Under the right circumstances, Nader's Green Party could find itself the leading force on the left.''

Unlike other third-party candidates, Nader never deluded himself that he was going to win. Instead, he realized that running for President can mean a guaranteed perch on the national soapbox. During his televised post-Election Day press conference, for example, he reeled off 17 separate issues--from fighting child poverty to universal health insurance to switching tax dollars from fancy sports stadiums to library and school construction. And that was just in answer to the first question.

But even a personality as forceful as Nader's may not be enough to build a party nearly from scratch, soothe the wounds inflicted on allies like Big Labor, and continually challenge the ''corporate-controlled government'' he likes to rail against. Nader had hoped to qualify the Greens for $7 million to $9 million in federal campaign and party-building funds by capturing 5% of the vote, but he came up short. Now, predicts Georgetown political scientist Stephen J. Wayne: ''Nader will continue to be a gadfly and leader of his own groups. But without money or an election, you can't really hold a minor party together. They'll collapse or implode just like the Reform Party did.''

Perhaps. But Nader also leaves the Greens with a mailing list of 240,000 supporters who gave $7 million to Nader's quixotic quest--nearly all in under $100 donations. Moreover, the movement may go on without Nader, who often serves as a kind of Johnny Appleseed for progressive causes. He has proved adept at founding and then spinning off left-leaning watchdog groups like Public Citizen and the Center for Automotive Safety.

Of course, Nader is already being branded a saboteur by furious Democrats. But he engaged the young, got people to the polls who might never have gone, and raised issues--undue corporate influence in Washington, the excesses of globalism, the failure of the drug war--that the major parties never mentioned. At his Nov. 8 news conference, he praised environmentalist icon David Brower, former executive director of the Sierra Club, who died recently. ''He never wavered. He never waffled. He never turned into a tactical person,'' said Nader. What Brower did was push the movement in the direction he favored. That may be Nader's legacy to the left--even if he's never forgiven.